A new generation of personal computers (PCs) and video game machines is now coming onto the market. These are capable of performing 3D graphics such as articulated figure (AF) animation. However, traditional research and approaches to computer AF animation has focused on the Animator. That is, they have focused on helping a professional Animator make AF animation for a video or film that he/she is making. With this new generation of PCs and game machines, the user can now direct the AF animation; however, the above mentioned Animator-based algorithms are too computationally expensive. A professional Animator making a film can work off-line. The animation does not have to be generated in real-time, and it does not have to be interactive. The Animator can develop each frame of the animation, taking as much time as is necessary, then store the frame onto a storage medium. Later, all the stored frames can be played back rapidly at video speeds. However, interactive applications, such as games or educational software, must generate the 3D user-directed AF animation at, or close to, real-time. The methods and systems constituting the invention are aimed at the interactive game or educational applications which use computer AF animation.
The focus of the invention centers on manipulating Motion Units (MUs). These MUs define the articulated figure's orientation (joint rotations) for each frame in an animation sequence. The game or application creator uses separate methods (including rotoscopy, key-frames, dynamics, and kinematics) to create an MU. Then the algorithms of the invention manipulate and run the stored MUs as the game user directs. The algorithms are simple and fast so as to not overburden lower end machines (which are often required to generate one frame of video 30 times per second). Yet the motions that are created by manipulating and mixing the MUs are fairly smooth and natural looking. Above all, the user is in control.
The invention provides simple user-based algorithms which can rapidly manipulate previously stored MUs.